Torsionally rigid, elastically flexible shaft coupling

ABSTRACT

In a torsionally rigid, elastically flexible shaft coupling at least two membranes are provided as transmission elements, which, on the inner and outer edge, have regularly spaced bores for clamping screws on the two coupling halves. In the intermediate area the membranes are provided with uniformly spaced openings. In order to increase the loading capacity of the shaft coupling, as well as to render possible the checking of the proper functioning of the membranes without dismantling them, the membranes are mutually offset by a fraction of the spacing of their openings. Moreover the fixing bores in a sector, which is equivalent to at the most half that of the openings, are arranged so that the bores for the clamping screws are aligned.

The invention relates to a torsionally rigid, elastically flexible shaftcoupling.

For such a shaft coupling, known from German Gebrauchsmusterschrift No.74 35 748, membranes are provided with asymmetrically formed openings sothat the spokes formed between the openings are inclined radially. Tothe inner and outer root of each spoke is assigned one hole,respectively for clamping the membranes at the inner and outer edge totheir two coupling halves by means of screws. There are no more fixingbores at the edge zones of the membranes other than said one hole perspoke. Therefore the membranes and spokes are forced into coincidencewhen stacked one on top of another. In such shaft couplings, theclamping screws of the membranes are strongly loaded, as the coincidingspokes of the stacked membranes, which are subject to bending stress,act on just one of the associated screws respectively. Thereby, the edgezones of the membranes extending between the clamping bores are notbrought into action for torque transmission as no screw couplings areprovided there.

As such shaft couplings are exposed to high alternating stresses, it isnecessary to check their operability from time to time. In order to doso, the coupling must be dismantled, particularly in order to check thespokes of the membranes for cracks and deformation. This is especiallyexpensive in time and cost.

The object of the invention is to increase the loading capacity of theshaft coupling. That type of coupling generally has at least twomembranes as force transmission elements. The membranes are provided attheir outer and inner edges with regularly spaced bores for clampingscrews to interconnect the two coupling halves. The intermediate areasof the membranes are provided with uniformly spaced openings. Thisstructure also makes possible the checking of the proper functioning ofthe membranes without dismantling them.

This object is attained by rotationally arranging the membranes so thatthey are offset with respect to each other by a fraction of the spacingof their openings. In addition, fixing bores are provided which aredisposed with a spacing which is at most half of the said openings sothat the bores for the clamping screws are aligned. This solution offersthe advantage that the spokes of the membranes are at least partiallyvisible through the openings in the membranes and they are accessiblefor inspection for deformation or cracks. On the basis of the mutuallyoffset membranes, different clamping screws respectively on the twocoupling halves are assigned to the spokes, so that the force of thetorque to be transmitted by the coupling is distributed more uniformlyover the inner and outer periphery of the coupling halves. Thetransmission of forces from the spokes of the membranes to the clampingscrews on the outer and inner edge of the membranes is distributed to agreater number of screws in this way and thus more harmoniously.

The purpose of having the openings have at least the angular width ofthe spokes between two openings is that, when using two membranes in theshaft coupling, the full width of the respective spokes of one membraneare visible through the openings of the other membrane and the spokesare easily controllable. For this purpose, the peripheral direction ofthe openings of the membranes have at least the same clear width whichcorresponds to the width of a membrane spoke passing between twoopenings. The spoke here referred to is that portion of the membranewhich extends between two adjacent openings. Indeed, it is known from DEGebrauchsmusterschrift No. 74 35 748 that the spokes of one membraneshall coincide with the openings of the adjacent membrane. However,there is no indication that this measure is to be provided for thepurpose of inspecting the membranes.

With the additional disposing of membranes axially, a sound test for themembranes is also envisaged, apart from a visual inspection. In thisway, the appropriate exposed membrane spoke can be struck and the lackof damage or damage can be ascertained from the sound picture generatedby the blow. A disc extending parallel to the membranes which providesprotection against spinning is disposed between the membranes and thecoupling half. This ensures uninhibited access to the membrane spokesfrom the side of the smaller coupling half. It protects the couplingfrom damage in the event the membranes fracture when spinning at highspeed, by preventing the smaller coupling half from being thrownoutward.

The refinement of shaping the openings with particular generally kidneyshape and rounded sides, as detailed below, ensures that, in the case ofshaft couplings having spokes tapering in width towards the outer edgeof the membrane, are adjusted in respect to the stress prevalent in themembrane under operational load. Furthermore, by limiting the membranespokes towards the inner and outer edge zone of the membrane in the formof rounded transitory areas, the notch effect is decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its objects are described in connection with thedrawings in which three exemplified embodiments of the invention areexplained in more detail below and in which:

FIG. 1 is an axial section through a shaft coupling having a package oftwo membranes as transmission elements between the two coupling halves,

FIGS. 2 to 4 are front views of membranes which differ by irregularlyspaced fastening bores at the inner and outer edge, on a smaller scalethan in FIG. 1,

FIG. 5 is a front view of a stratified package of two mutually offsetmembranes, as the first exemplified embodiment,

FIG. 6 is a half-section through the membrane package along the lineVI--VI in FIG. 5, on an increased scale,

FIGS. 7 and 8 are a stratified package of three membranes, as a secondexemplified embodiment, in a manner of representation corresponding toFIGS. 5 and 6,

FIGS. 9 and 10 are a third exemplified embodiment, a stratified packageof four membranes, likewise in a manner of representation correspondingto the preceding FIGS. 5 to 8.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The torsionally rigid, elastically flexible shaft coupling 2 shown inFIG. 1 is provided with transmission elements, disposed perpendicular toits axis of rotation 3, in the form of a package of membranes 4, whichconnects the two coupling halves 5 and 6 to one another. The radiallylarger coupling half 5 bears a spacer ring 8 as well as a clamping ring9 at the outer edge of its flange 7. With its outer edge 10, themembrane package 4 engages between the spacer ring 8 and the clampingring 9. These components are penetrated by clamping screws 11 uniformlyspaced along the periphery of the coupling half 5 and are clamped to theflange 7 by means of nuts 12.

The enclosed coupling half 6 has an intermediate sleeve 13 having aflange 14 which points inwards. To this flange 14 is assigned a clampingring 15, the cross section of which extends radially as far as theproximity of the spacer ring 8 of the external coupling half 5. The disk16 formed in this way extends parallel to the membranes 4 between theseand the flange 7 of the coupling half 5 and provides protection againstthe smaller coupling half 6 being thrown outward in the event of themembrane breaking. The flange 14 of the intermediate sleeve 13, theinner edge 17 of the membrane package 4 and the clamping ring 15 arealso held together by uniformly spaced clamping screws 18 and theassociated nuts 19.

The membrane 20 shown in FIG. 2 has the shape of a circular ring. At itsouter edge 21 it is provided with forty-eight bores 22 for the passageof the clamping screws 11. The bores 22 have a uniform spacing t₂ of 7°30', starting from the ordinate O₂. At its inner edge 23 the membrane 20has twelve bores 24 for the clamping screws 18 of coupling half 6. Thesebores 24 have a spacing T₂ of 30°, starting from ordinate O₂.

In the intermediate area, the membrane 20 is provided with six openings25 with uniform spacing D of 60°. The openings 25 constructedsymmetrically in relation to the radii are approximately kidney-shapedand, when radially extended towards the outer edge 21, are limited inparallel at a common distance from the outer edge 21. They are roundedat both sides 26, and then open into a curve 27 having a larger radius,directed towards the inner edge 23 of the membrane 20. A spoke 28,situated between two openings 25, therefore tapers from the inner edge23 towards the outer edge 21 of the membrane 20. Its smallest width B₂there is less than the clear width W₂ of the openings 25 measured in theperipheral direction.

The membrane 30 shown in FIG. 3 differs from the design described aboverelating to FIG. 2 in that, starting from ordinate O₃, forty-five outerbores 32 with a spacing t₃ of 8° are provided, and fifteen inner bores34 with a spacing T₃ of 24° are provided.

The membrane 40 shown in FIG. 4 has, on the other hand, forty-eightbores 42 at the outer edge 41 with a spacing t₄ of 7° 30', starting fromordinate O₄. At the inner edge 43 of membrane 40 are disposed twelvebores 44 with a spacing T₄ of 30° starting 15° from the ordinate O₄.

The first exemplified embodiment, shown in FIGS. 5 and 6, of a membranepackage 50 for use in the shaft coupling described at the beginning(FIG. 1), consists of two membranes 20 in the design according to FIG.2. The membrane 20' placed on top in FIG. 5 occupies the same positionas that in FIG. 2, whereas the lower membrane 20" having the same shapeis offset by a spacing T₂ ". By this arrangement, both the outer bores22 and also the inner bores 24 for the clamping screws 11 and 18,respectively, of shaft coupling 1 align. On the other hand, the openings25' and 25" respectively of the two membranes 20' and 20" are mutuallyoffset by half a spacing D so that the spokes 28" of the lower membrane20" are visible through the openings 25' of the membrane 20' placed ontop. By this, the intended visual inspection of the spokes is madepossible even for the membrane which, in the case of the membranepackage mounted in the shaft coupling 1, lies on the side of the disk 16serving as protection as explained above. As the half-section displayedin FIG. 6 shows, the two membranes 20' and 20" of the membrane package50 may be disposed with axial distance. For this purpose between the twomembranes 20' and 20" are inserted spacer rings 60 and 61, which followthe outer edge 21 and the inner edge 23 of the two membranes and whichare provided with openings for the clamping screws 11 and 18 of theshaft coupling 2 according to FIG. 1.

The second exemplified embodiment shown in FIGS. 7 and 8 of a membranepackage 70 has three membranes 30 in the design according to FIG. 3.Starting with three congruent, superposed membranes 30, the top membrane30' is in the same position as that in FIG. 3; on the other hand themembrane underneath 30" is offset in the anti-clockwise direction by thespacing T₃ ", the lowest membrane 30" is offset in relation to themembrane 30' by the spacing T₃ '" in the clockwise direction. Even withthis arrangement the outer bores 32 and also the inner bores 34 of allthe membranes align. The full width of the spokes 38" of theintermediate membrane 30" are visible through the openings 35' of theupper membrane 30' and the spokes 38'" of the lower membrane 30'" arepartially visible through the openings 35" of intermediate membrane 30".However, the reduced visibility of the spokes 38'" of the bottommembrane 30'" is completely adequate for checking for cracks and for asound test. Also for membrane package 70 spacer rings 80 and 81 areinserted between the individual membranes 30', 30" and 30'" at the outeredge 31 and at the inner edge 33 (FIG. 8).

The membrane package 90 shown in FIGS. 9 and 10 as the third exemplifiedembodiment is constructed from two membranes 20 in the form according toFIG. 2 as well as from two membranes 40 according to FIG. 4. At the topthe membrane package 90 is formed by membrane 20', beneath that by twomembranes 40' and also 40", and at the lowest point by a membrane 20".Taking as a basis the membranes, which are superposed in the positionaccording to FIGS. 2 and 4 and the respective openings 25 and 45 ofwhich are congruent, the membrane 40' beneath the top membrane 20' isstaggered by half a spacing T₄ ' in the anti-clockwise direction. Themembrane 40" i placed in third position is staggered in relation to thetop membrane 20' by half a spacing T₄ " in the clockwise direction.Finally, the lowest membrane 20" is staggered by a spacing T₂ " inrelation to the top membrane 20'. The spokes 48' of the subjacentmembrane 40' are thus visible inside the openings 25' of the topmembrane 20'. Through the cross-section bordered by the openings 25' ofthe top membrane 20' and through the openings 45' of the membrane 40' insecond position, the spokes 48" of the subjacent membrane 40" arepartially visible. Lastly, the slightly overlapping openings 45' of themembrane 40' give an unobstructed view of the spokes 28" of the lowestmembrane 20". Also in the third exemplified embodiment spacer rings 100and 101 are inserted between the individual membranes 20', 40', 40" and20" of the package 90 at the outer and inner edge.

I claim:
 1. Torsionally rigid, elastically flexible shaft couplinghaving two coupling halves to be coupled and a coaxial membrane arraycomprising at least first, second and third coaxial membranes astransmission elements between the coupling halves;the membranes eachhaving an outer edge and an inner edge; and having a first plurality ofregularly angularly spaced outer bores toward the outer edge and asecond plurality of regularly angularly spaced inner bores toward theinner edge; all the inner bores being at the same radial location aroundthe membranes, and all the outer bores being at the same radial locationaround the membranes; the membranes being in relative angular positionssuch that respective inner and outer bores in the coaxial membranes arealigned, clamping means being received in the aligned bores toward theouter and inner edges; each membrane having an intermediate area, withuniformly angularly spaced openings through the intermediate area; themembranes being mutually angularly offset by a fraction of the angularspacing of their respective spaced openings for providing access throughthe opening in each membrane to the area between openings of anothermembrane, and the bores being disposed with an angular spacing which isat most half the spacing of the openings so that around the membrane andbetween two adjacent openings on each membrane, there is both arespective outer bore for each of the membranes and a respective innerbore for each of the membranes which are aligned, the aligned boresreceiving the clamping means; wherein the part of a membrane betweeneach two openings comprises a spoke; the outer bores and the inner boreson the membrane being placed and spaced so that, with the membranesangularly offset, the spokes of one of the membranes are at leastpartially behind and are visible through the openings in the coaxialmembrane adjacent, while the inner and outer bores on the membranes arealigned for receiving respective clamping means; and wherein eachmembrane is angularly offset from the others to that the spokes of thefirst membrane, at one axial end of the array of membranes, are at leastpartially behind and visible through the openings of all the othermembranes; and the spokes of the second membrane, between the first andthird membranes of the axial array, are at least partially behind andvisible through the openings in the third membrane at the other axialend of the array of membranes.
 2. Shaft coupling according to claim 1,wherein in the angular direction, spokes of the membranes alternate withthe spaced openings of the membranes, and each opening has at least thesame clear width as the width of the membrane spoke passing between twoof the openings.
 3. Shaft coupling according to claim 2, wherein themembranes are axially spaced from each other.
 4. Shaft couplingaccording to claim 3, wherein one of the coupling halves is radiallylarger than the other coupling half, and a disk coaxial with themembranes and extending parallel to the membranes extends radiallyoutward from the smaller one of the coupling halves and toward theradially larger one of the coupling halves for limiting radial movementof said smaller coupling half.
 5. Shaft coupling according to claim 2,wherein the spokes between the openings are mostly tapering in widthtowards the outer edge of the membrane; the openings each beingsymmetric in relation to a radius of the membrane angularly through themiddle of the opening, and being rounded at both angular sides andopening into a curve having a larger radius than the rounding of theangular sides and directed towards the inner edge of the membrane.